Ultrastructural changes in the cerebellum of nursling rats given corynetoxin, the aetiological agent of annual ryegrass toxicity.

Nursling rats were given a lethal dose of corynetoxin and the sequential morphological alterations in the cerebellum were examined at daily intervals up to 3 days post-inoculation. Ultrastructural changes were those of cerebral vascular damage, which was usually focal in affected endothelial cells, and resulted in vascular stasis or thrombosis. These changes ultimately constituted a failure of perfusion in focal areas of brain parenchyma supplied by these vessels, resulting in necrosis.